The present invention relates to a method for detecting and/or quantifying a hapten in a homogeneous phase, as well as the device for detection and/or quantification, in particular the kit allowing the screening and/or the assay of a hapten in a homogeneous phase.
During the past few years, major advances in the field of biotechnology have made it possible to develop immunoassays allowing the assay of haptens in a homogeneous phase, that is to say of small-sized molecules of natural origin or which are obtained by the synthetic route and which are used in particular for treating animals or humans.
Such molecules may be, for example, active components of medicaments, hormones, anabolic steroids and the like.
To facilitate the application of the tests for screening and/or assaying these haptens, attempts have been made to develop immunoassays which can be used in a homogeneous phase.
Enzymatic immunoassays have thus been proposed. They are xe2x80x9csubstrate labelled fluorescent immunoassayxe2x80x9d, xe2x80x9capoenzyme reactivation immunoassay systemxe2x80x9d, xe2x80x9cenzyme multiplied immunoassay testxe2x80x9d and xe2x80x9cenzyme channeling immunoassayxe2x80x9d described by Voller and Bidwell (Voller A., Bidwell D. W., in Alternative Immunoassays, Collins W P Ed. John Wiley, Chichester, pp. 78-79 (1986)) as well as the cloned enzyme donor immunoassay (Henderson et al., Cli. Chem., 32, 9, pp. 1637-1641 (1986)).
Patent Application EP-0117648 describes an immunoassay of steroids in phase based on the inhibition of the clotting of milk, this assay giving information on the fertility of milk-producing domestic animals.
However, to date, no success has been achieved in developing, immunoassays working in a homogeneous phase which are sufficiently sensitive, specific and reproducible to allow their widespread use in the assay and/or detection of a large number of haptens in clinical biology and in various media (blood, urine and the like).
The iodine-based systems used up until now have the disadvantage that practically all iodides are oxidizable in the air, generating iodine which is lost by sublimation. This therefore constitutes a first source of instability. Moreover, starch paste is easily degraded by bacteria or fungi, which constitutes another source of instability.
Patent Application FR-2,339,172 describes a reactive system for determining if uric acid or another material oxidizable by iodine exists in a liquid in a proportion greater than a predetermined quantity in an alkaline medium, said reagent comprising a water-activatable iodine generator capable of liberating in situ an appropriate quantity of free iodine with an indicator to detect the presence of iodine. The iodine generator and the indicator are applied to a test strip. Consequently, such a device only works in the dry state and therefore remains dependent on an analysis on a solid system.
The present invention aims to obtain a method and a device for screening and/or assaying a hapten in any type of homogeneous phase (blood, serum, urine, milk and the like) which are sufficiently sensitive, specific and reproducible.
In particular, it is sought to obtain a method and a device which make it possible in particular to detect haptens present in a human or animal physiological fluid, at concentrations of the order of 100 pM or higher, or even at concentrations of the order of 10 pM or higher.
A specific aim of the present invention seeks to optimize the sensitivity of said method and device by reducing the xe2x80x9cbackground noisexe2x80x9d observed in the devices and methods of the state of the art.
A final aim of the present invention seeks to obtain a device which would be capable of being stored for a longer period without contamination or degradation.